1. Field of the Invention
The invention relates to a high speed logic signal level shifter, and specifically to a circuit for transferring a fast logic signal across a high voltage difference between two circuit sections in an integrated circuit.
2. Background Information
A high speed DC coupled logic level translator is particularly useful for high speed, high current CMOS drivers. High speed, high current drivers are used in applications such as medical ultrasound and non-destructive testing, where MOSFET power transistors must be driven quickly with signals originating in low voltage logic circuits. Additional applications in switch mode power supplies and other circuits requiring the fast switching of MOSFET power transistors are possible.
A critical aspect of a high speed DC coupled logic level translator circuit is that circuit must transfer the signal changes with minimum propagation delay time, and have minimal sensitivity to changes in the voltage supply voltage VPP and VNN. Problems with the logic signal transfer can be caused by transient or fast changes in the voltage VPP and VNN interfering with the coupling of the logic signals across the voltage barrier. One means which has been successfully used to overcome this problem is to use large pulsed currents in the transfer circuitry. The current pulses are larger than any capacitive displacement currents caused by expected voltage transients, so the circuit operates without error. Power is minimized by use of very short current pulses to transfer information about logic state changes. However, a simpler solution not requiring large pulsed currents in the transfer circuitry would be desirable.
Therefore, a need exists to provide a device and method to overcome the above problem. The device and method will provide a high speed logic signal level shifter. The high speed logic level shifter must be able to transfer a fast logic signal across a high voltage difference between two circuit sections in an integrated circuit. The high speed logic level shifter must be able to transfer a fast logic signal across a high voltage difference between two circuit sections in an integrated circuit without using large pulsed currents in the transfer circuitry.